This is an old Swedish folk-magic spell and is supposed to be very old. The purpose here is to stop the fire from dying out in the oven or on the hearth. It should be used in the evening, when the embers are covered with ashes. The interesting thing here is that the names of various reproductive organs are used as Names of Power:
aldrig skall elden
slockne i mitt hus.
Translation (Trigger Warning!):
never the fire
will die in my house.